WEST CALDWELL — Four students were taken out of a West Caldwell vocational school in handcuffs and charged with disorderly persons offenses this afternoon, hours after the building was placed on lockdown when a staff member received information that a student may have brought a gun into the facility, a law enforcement source told The Star-Ledger this afternoon.

The students were not charged in connection with reports that a firearm was brought into Essex Valley School, and no weapon has been found, according to the source, who asked to remain anonymous because they were not authorized to discuss the matter with the media.

The school was placed on lockdown earlier this afternoon as West Caldwell Police and members of the Essex County Sheriff's Office were called into investigate reports that a student had brought a gun into the building, West Caldwell Police Chief Michael Bramhall said in a statement.

Officers from his department and the Essex County Sheriff's Office K-9 Unit arrived at Essex Valley School on Henderson Drive shortly after 1 p.m. when a staff member received information that a weapon had been brought onto the school's grounds.

"As a precaution a lock-down procedure is in effect and a thorough search of the school is under way. As of this afternoon no weapon has been located and the search is continuing room by room," Bramhall said in a statement.

Bramhall said no one will be permitted to leave the school's grounds until police complete their investigation. Students are usually dismissed at 2:36 p.m., he said.

Students were rounded up in the gymnasium and individually searched, according to the source, and officers are now scouring lockers and other parts of the building. The four students who were charged with disorderly persons apparently had some kind of altercation with each other while officers were conducting searches in the gym, the source said.

Essex Valley School is a "therapeutic alternative" school which takes in students that have struggled in other more traditional schools, according to its website. The school offers both vocational services and one-on-one counseling, and expanded its roster of counselors in February, according to a school newsletter.